334 ZOOLOGY. 



larynx, and the condition of the glottis (glottides) can only 

 be modified by those which raise or depress the trachea. 



[Note on the tracheal dilatation of the cassowary of New Holland. 

 I discovered this remarkable dilatation, or pouch, connected 

 with the trachea of the cassowary in 1824, and described it in the 

 Edinburgh Philosophical Journal, 1. x. It appears from what I 

 learn from Meckel, that Fremery* had, in 1819, seen the opening 

 in the trachea, but was entirely ignorant of the pouch, or bag, 

 which he had no doubt cut away unskilfully whilst dissecting 

 the neck. When in Paris, in 1825, M. Cuvier expressed a wish 

 to see the trachea and pouch, and his assistant soon found for us 

 the trachea, but, as in the case of Fremery, the pouch had been 

 cut away and lost. From the same authority (Meckel) I learn 

 that this singular structure had been afterwards described by 

 Hausmann and Wedemeyer. 



Fig. 320. Trachea of the Emu, or Cassowary of New Holland. 



The deficiency in the tracheal rings commenced at the 52, 

 and extended to the 62; by this large opening the interior of 

 the trachea communicated with a pouch not much smaller than 

 the human head. I at first supposed it to be in part muscular, 

 but I could not verify this on the dried preparation. The dia- 

 meter of the opening was about 2^ inches. I believe it is found 

 in both sexes. The purposes it serves in the economy of the 

 cassowary have not been discovered ; at the time I made the dis- 

 covery, I fancied that it might serve as a swimming bladder to 

 the bird if suddenly placed in difficulty by the inundations for 

 which Australia was remarkable. But this was, of course, a mere 

 conjecture. The pouch is situated at the lower part of the neck, 

 immediately above the sternum, and is thus well placed for a 

 swimming bladder. It can be filled with air or emptied at the 

 will of the bird. Meckel examined the bird during life, and 

 observed that the pouch did not swell when the bird was made 

 to run, but, on the contrary, evidently became dilated when at 

 rest. R. K.] 



442. Birds are oviparous, and the young require no 



* Spec. Zool. Sistens Obs. Pr. Osteol de Casuaris. Nov. Holl. Tras. ad Ep. 

 1819. 



